The present invention relates generally to projection television sets, and more particularly to sealing devices for the optical unit of a projection television set.
Projection television sets are a popular alternative to picture tube television sets, as they provide relatively large viewable screens that cannot be efficiently produced using conventional picture tubes. Projection television sets typically include an enclosure with an optical unit, a mirror, and electronic components for receiving and projecting an image onto a screen assembly mounted on the front of the enclosure.
As shown schematically in FIG. 1, the optical unit 10 generally includes a set of projection units 20R, 20G, and 20B. Each projection unit projects an image, generally of a single color of light (red, green, or blue), onto the mirror M in the enclosure, which focuses the image onto an inside surface of the screen S. The projection units are mounted to a bracket 50 that is mounted to the enclosure (not shown). The bracket 50 holds the projection assemblies in place within the enclosure at their correct angular orientation.
Each projection unit includes a cathode ray tube (CRT) (22R, 22G, 22B), a projection lens assembly (45R, 45G, 45B), and a spacer (28R, 28G, 28B) interposed between the CRT and lens assembly. A liquid coolant is typically introduced between the projection lens and CRT into a cavity sealed by the spacer, CRT, and projection lens (see FIG. 3). The liquid coolant cools the face of the CRT by dissipating the heat radiating from the CRT and transferring it to the spacer. By lowering the operating temperature of the projection unit, optical performance is enhanced and component life is increased.
The existing optical units, however, have their disadvantages. From a cooling standpoint, the multiple spacers tend to be inherently inefficient. In addition, the packing used to seal the coolant chambers formed by the CRT-spacer-lens assemblies tends to be prone to misalignment during assembly and, thus, prone to leaks. Lastly, construction and assembly of the multiple components that go into existing optical units tends to be cumbersome and, thus, labor intensive. Therefore, it would be desirable to provide optical units that are easy to assemble and install, and that include a more efficient and reliable cooling system.
The present invention is directed to an improved optical unit of a projection television set, which facilitates manufacturability, optical performance, and component longevity. In one particularly innovative aspect, the optical unit of the present invention combines a bracket and individual projection unit-spacers into a single spacer-bracket. Moreover, a spacer-bracket in accordance with the present invention preferably comprises interconnected coolant chambers and reservoirs.
In another particularly innovative aspect, the packing members used to seal the coolant chambers include position or alignment retaining components. Such components aid in the assembly of the optical unit and tend to reduce the likelihood of coolant leaks.
In another innovative aspect, a coolant chamber fill port closure member includes a push plug and packing sleeve.
In another innovative aspect, the CRT holder is coupled to the spacer-bracket via screws and load distributing mounting brackets.
Other objects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.